Hundreds of fighters from the IMU are believed to have settled in Pakistan's tribal region of Waziristan after the downfall of the hard-line Taliban in neighboring Afghanistan in late 2001.
Pakistani security forces hunting Al-Qaeda fighters have since killed or captured a handful of IMU militants, and some IMU loyalists have been extradited to Uzbekistan. But IMU leader Tahir Yuldosh -- one of Uzbekistan's most-wanted fugitives -- is thought to be alive and hiding in Pakistan.
Uzbek authorities have also complained that their Pakistani counterparts do not grant them access to dead or captured Uzbek militants.
Karimov and Pakistani President Pervez Musharraf discussed security on May 2, and they signed an agreement on combating terrorism.
On New Delhi's Heels
Ahmed Rashid is a Pakistani-based expert on Central Asia and terrorism. He suggested Karimov probably raised concerns about IMU encroachments and related security issues with Pakistani officials.
Rashid also said he thinks the timing of Karimov's visit -- one week after talks with Indian Prime Minister Manmohan Singh -- is significant.
"I am sure the Indians must have given him a lot of intelligence regarding that [counterterrorism], because there is a proxy war -- or a battle, at least -- going on between India and Pakistan," Rashid said. "There is a great of deal of tension between India and Pakistan regarding Afghanistan and Central Asia."
Rashid said Pakistan is motivated by its rivalry with India and its desire for access to Central Asian markets. Islamabad would also like to re-direct Central Asian trade flows through Pakistani ports.
"Musharraf is very keen to improve relations with Central Asia," Rashid said. "The first thing is that he wants to offset the Indian influence in Central Asia. India [will have] an air base in Tajikistan. It has very close relations with all the Central Asian states. It's buying up oil, gas, and drilling rights in Kazakhstan [and] in Azerbaijan. At the moment, certainly, Pakistan has very poor relations with the Central Asian republics."
Karimov's Charm Offensive
The Uzbek president is keen to demonstrate that the Uzbek leadership has not been weakened by the souring of relations with the West. He has consistently rejected U.S. and European Union calls for an independent probe into his government's deadly crackdown in Andijon a year ago. Karimov evicted U.S. troops from Uzbek soil in late 2005. The European Union has introduced a weapons embargo and an entry ban for 12 senior Uzbek security officials.
President Karimov has been traveling extensively since Andijon. He went to China last year, recently visited Kazakhstan, Russia, and South Korea, and hosted the Indian prime minister in Tashkent in April.
Karimov's delegation in Pakistan includes his ministers of foreign affairs, justice, finance, and foreign trade, as well as his central-bank chief.
Getting Down To Business
Pakistani President Musharraf highlighted common goals in the areas of trade and investment.
"On the bilateral trade side, we showed mutual desire to enhance our trade, commercial, and economic relations -- which at the moment are extremely low," Musharraf said. "We expressed a mutual desire of developing communication linkages between our two countries through road and rail network, and we offered openly the use of our communication network in Pakistan and our ports at Gwadar and Karachi for the access of Uzbek trade and interaction with the world."
A Pakistani Foreign Ministry information officer, Nadeem Hotiana, told RFE/RL that the two sides signed nine agreements in all. They include deals on bilateral trade, small and mid-size business, and agriculture -- in addition to the counterterrorism agreement.
Uzbek President Karimov called his meeting with Musharraf wide-ranging, and "open and constructive." With both men eager to open avenues of dialogue and boost their influence in the region, even the slightest thaw relations is likely to be viewed positively from Islamabad and Tashkent.
(RFE/RL's Radio Free Afghanistan correspondent Najib Aamir and Uzbek Service correspondent Farruh Yusupov contributed to this report.)