"There are increasing signs that everyone will be able to agree on this," Pistorius told reporters in Brussels when asked about reports that the U.S. is open to permitting Kyiv to forgo a formal candidacy process required of some other nations in the past.

"I would be open for this," said Pistorius, speaking on the sidelines of a meeting with his NATO counterparts at the alliance's headquarters.

The Washington Post reported on Thursday that the United States is giving tentative backing to a plan that would remove barriers to Ukraine's entry into NATO without setting a timeline for its admission.

It quoted a senior U.S. official as saying Washington is "comfortable" with a proposal from NATO Secretary-General Jens Stoltenberg that would allow Kyiv to circumvent the alliance's so-called Membership Action Plan (MAP).

Since 1999, most countries aiming to join NATO have participated in this programme, which is designed to help candidates meet certain political, economic and military criteria.

By shortening the process, the U.S. hopes to bridge divisions among member nations over Kyiv's path to joining the transatlantic military alliance, the Washington Post reported.

"This is a potential landing zone in this debate," it quoted one official as saying.

However, the proposal would still require Ukraine to carry out reforms and, contrary to the wishes of Eastern European allies, it would not attach a time frame for Ukraine's accession, according to the paper.

At its Bucharest summit in 2008, NATO agreed that Ukraine - which like Russia was part of the Soviet Union until its 1991 demise - would eventually join the alliance.

But NATO leaders have so far stopped short of taking concrete steps that would lay out a timetable for bringing Kyiv into the alliance, something Eastern allies and Ukraine itself are pushing for.