Pakistan confirmed late Thursday that the U.S. has imposed travel restrictions on Pakistani diplomats.

“The restrictions on our diplomats will be implemented from May 11, and these will be on a reciprocal basis,” Foreign Office spokesman Mohammad Faisal told reporters at a briefing.

But negotiations are ongoing between the two sides on the matter, Faisal added.

Earlier, local and foreign media reported that U.S. authorities had planned to impose travel restrictions on Pakistani diplomats in the U.S. from May 1, but the plan was delayed until May 11.

Under the new plan, Pakistani diplomats in Washington and at consulates in other U.S. cities will be barred from traveling more than 40 kilometers (about 25 miles) from their posts without prior permission, the local Dawn daily reported.

U.S. authorities have complained that Pakistan’s government has imposed travel restrictions on their diplomats.

“Our diplomats are under restrictions and they can travel farther [than the capital Islamabad], but they have to notify the government of Pakistan. So we’ve taken reciprocal steps,” Under Secretary for Political Affairs Thomas Shannon told U.S. state-run media Voice of America last week.

Pakistani authorities have said that such measures have been adopted to ensure the security of foreign missions and their employees and the country has no other motives.

Relations between the two allies in the war against terrorism have been tense since President Donald Trump assumed office in January last year, mainly due to a clash of interests in war-torn Afghanistan.