Ukraine's new Prime Minister Viktor Yanukovych has said Kiev is not ready to join Nato because of public opposition to such a move.
An anti-Nato slogan featured in Mr Yanukovych's poll campaign
"We will have to take a pause," Mr Yanukovych said after talks with top Nato and EU officials in Brussels.
At the same time, he said Kiev would continue to boost ties with the EU.
Mr Yanukovych was named PM in August by his arch-rival President Viktor Yushchenko, on condition that he followed his pro-Western agenda.
The move capped a dramatic comeback for Mr Yanukovych, who was ousted in Mr Yushchenko's "Orange Revolution" in 2004.
On his first visit to Brussels as prime minister, Mr Yanukovych said full Nato membership only had limited support among Ukrainians.
He said Kiev was taking a pause "because of the political situation in Ukraine".
"But the time will come when a decision will be made... For the time being we are looking at enlargement of our co-operation with Nato," he said.
Opposition to Nato membership is particularly strong in eastern and southern Ukraine - the electoral strongholds of Mr Yanukovych's party.
Russia has also voiced strong opposition to Ukraine joining Nato.
Kiev had earlier expressed hopes of joining the world's biggest defence alliance in 2008.
Mr Yanukovych said Ukraine would continue reforms aimed at bringing the country closer to the EU.
"We have the firm intention to have excellent relations with the EU and stable relations," he said after talks with EU External Relations Commissioner Benita Ferrero-Waldner.
Mr Yanukovych expressed hopes that stronger ties "will bring us in the long term to accession of the European Union".
Ms Ferrero-Waldner said the 25-member bloc had no plans to offer Kiev membership "at this moment".
Instead, she suggested the two sides negotiate what was described as an enhanced agreement that would include a free trade pact.
Earlier on Thursday Mr Yanukovych signed a deal to let the EU install meters on oil and gas pipelines across Ukraine's borders to help settle any disputes about supplies.
Mr Yanukovych - who favours closer ties with Russia - was initially declared the victor in the 2004 presidential polls, but the result was then annulled by the Supreme Court, which ruled that the vote was fraudulent.
Mr Yushchenko was elected president in the re-run of the second round ordered by the court.
In March, Mr Yanukovych's Party of Regions polled the most votes in parliamentary elections, but failed to secure a majority.