This 23 October 2010 article from the internal NSA newsletter FAD Digest describes how US-Japanese intelligence cooperation has begun to operate more openly: see the Intercept article Japan Made Secret Deals With The NSA That Expanded Global Surveillance, 24 April 2017.
This internal NSA information paper, dated 19 April 2013, describes a “far reaching technical and analytic relationship” with Israel’s SIGINT National Unit (ISNU): see the Intercept article Cash, Weapons and Surveillance: the U.S. is a Key Party to Every Israeli Attack, 4 August 2014.
This April 2013 agenda prepares for a visit of senior officials from the German BND. Subjects to be disussed include Special Source Operations: see the Der Spiegel article New NSA Revelations: Inside Snowden’s Germany File, 18 June 2014.
A Memorandum of Understanding (MOU) between the NSA and the Israeli SIGINT National Unit that allows the NSA to share “raw SIGINT data” with Israel. The agreement was reached in March 2009, although the MOU itself is undated: see the Guardian article NSA shares raw intelligence including Americans’ data with Israel, 11 September 2013.