German Foreign Minister Frank-Walter Steinmeier has denounced Russia's "attempt to splinter Europe" by backing an independence referendum in Ukraine's Crimea region earlier this month.
"The referendum in Crimea last Sunday, the decision by the Russian Federation and finally the integration of Crimea to the territory of the Russian Federation, are events that are in violation of the international law and conjure up the danger of splitting Europe," Steinmeier said.
"Our experience and lessons from decades ago tell us that this is a situation we cannot accept, as we cannot allow bloodshed to repeat again."
Russian President Vladimir Putin signed a law formalizing Crimea's annexation on March 21, despite U.S. and European sanctions.
Speaking in Kyiv on March 22 after meeting with Ukraine's acting President Oleksandr Turchynov, Steinmeier said he hoped the first Organization for Security and Cooperation in Europe (OSCE) monitors would arrive in Ukraine to support de-escalation efforts in the next couple of days.
Canadian Prime Minister Stephen Harper, who was also in Kyiv on March 22, said after talks with Ukrainian Prime Minister Arseniy Yatsenyuk that Russia's actions risked sparking a new arms race.
"Ukraine relinquished its nuclear weapons that it inherited from the former Soviet Union on the basis of an explicit Russian guarantee of its territorial integrity. By breaching that guarantee, President Putin has provided a rationale for those elsewhere, who needed little more encouragement than that already furnished by pride or grievance, to arm themselves to the teeth," Harper said.
Earler on March 22, Moscow slammed the second wave of sanctions imposed by the European Union over the Crimean crisis as "divorced from reality."
On March 21, the EU added 12 Russians and Ukrainians to a list of people targeted by asset freezes and travel bans, bringing to 33 the number of figures targeted by the European bloc.
Russian Foreign Ministry spokesman Aleksandr Lukashevich said on March 22 that Russia reserved the right to "give a comparable answer to the actions taken."
In a separate statement, the ministry expressed hope that the decision to send international monitors to Ukraine will help "overcome the internal Ukrainian crisis, stop rampant nationalist banditry, [and] eradicate ultra-radical tendencies."
Russia agreed late on March 21 to join the 56 other members of the OSCE in a consensus decision to send a monitoring mission to Ukraine. It added that the "mission's mandate reflects the new political and legal realities and does not extend to Crimea and Sevastopol, which have become part of Russia."
The OSCE had said the observer team -- numbering at least 100 -- will gather information over six months on the security situation "throughout" Ukraine.
U.S. chief envoy Daniel Baer said the observers will start deploying within 24 hours of the March 21 decision.
The OSCE hopes the monitoring team will be able to prevent an escalation of tensions in Ukraine's east and south -- regions that have large Russian-speaking populations.
It will initially be deployed in nine places, including Donetsk, a major city in eastern Ukraine.
Crimea Tensions Rise As Ukrainian Bases Under Pressure
In western Crimea, pro-Russian protesters have stormed a Ukrainian air base. Correspondents at the scene said some 200 unarmed demonstrators yelling "Russia! Russia!" broke through to the base in the town of Novofedorivka and started smashing windows.
Ukrainian military personnel barricaded themselves inside buildings and threw smoke bombs at the intruders from the roof.
Meanwhile, Russian troops have surrounded a Ukrainian air base in Belbek, near Sevastopol, and issued an ultimatum to forces inside to surrender.
The deputy commander of the base, Oleg Podovalov, said Russian troops "gave us an hour to surrender or they will start storming."
Meanwhile, several thousand people attended a pro-Russian rally on on March 22 in the eastern Ukrainian town of Donetsk. Many chanted slogans in favor of a referendum on seceding from Ukraine.
Earlier, Russian Defense Minister Sergei Shoigu ordered the Black Sea Fleet's command to let Ukrainian armed forces servicemen wishing to leave proceed to Ukrainian territory in an organized manner.
A Defense Ministry spokesperson said on March 22 that the Ukrainian soldiers could drive away in their own vehicles, escorted to the border by Russian military police.
As of March 21, less than 2,000 Ukrainian troops had expressed the wish to leave for Ukraine, according to the ministry, out of more than 18,000 Ukrainian troops stationed in Crimea.
The ministry said Russian state flags had been raised at 147 Ukrainian armed forces' bases and units in Crimea. Russian Navy flags have been raised on 54 Ukrainian naval ships.
Also, Crimea held a joint funeral for a Ukrainian soldier and a pro-Moscow militiaman killed this week -- the only casualties since Russian forces took over the region.
Sergei Aksyonov, the region's prime minister, said at the funeral in the Crimean capital of Simferopol that the two were "Crimean heroes."
Mikhail Sheremet, the leader of the pro-Moscow militia in Crimea, said the two men were victims of "a provocation" during a gunbattle in Simferopol on March 18. Sheremet said the deaths were still being investigated by local authorities.
Meanwhile, UN Assistant Secretary-General for Human Rights Ivan Simonovic arrived in the Crimean capital, Simferopol, on March 21 on a two-day visit to start preparatory work for a UN human rights monitoring mission in the peninsula.
A UN spokesman said the UN had four international monitors and seven national monitors in Ukraine -- a number that will increase -- and was already operating in two major cities in the pro-Russian east, Donetsk and Kharkiv.
Simonovic plans to visit the port of Sevastopol on March 22 for further meetings before returning to Kyiv.
At a forum in Brussels on March 21, Ukraine's acting Foreign Minister Andriy Deshchytsya insisted Crimea was not lost.
"We believe that Crimea is an integral part of Ukraine," Deshchytsya said. "Our navy and soldiers did not shoot because they showed restraint and all the world have seen this, how the spirit and courage can confront the Kalashnikovs."
With reporting by AFP, BBC, Reuters, Interfax, and ITAR-TASS