Secretary of State Rex Tillerson renewed pressure on the U.S.'s NATO partners on Friday to step up their contributions to the alliance's budget.

Speaking to reporters in Brussels, Tillerson said that all 28 members need to guarantee the alliance has all the financial resources available.

Tillerson is attending his first NATO meeting on Friday, which was moved forward to ensure he would be present. The original plan was to meet on April 5 but Tillerson could not make that date given that he is due to meet with Chinese officials. The other 27 countries agreed to meet earlier so Tillerson could attend.

Meanwhile, Linas Linkevicius, the Lithuanian minister of foreign affairs, told CNBC on Friday that it was the "very beginning" of the new administration in the U.S. adding that it was important to show flexibility.