** Trump tariffs are likely to hurt US Aerospace and Defense sector by increasing costs and disrupting supply chains, with most demand impacts remaining "unknowable", says TD Cowen

** Despite these challenges, defense stocks like Boeing BA.N , RTX RTX.N , and Howmet Aerospace HWM.N are favored for their unique strengths and oversold values

** BA down 2.4%, while HWM and RTX slip 4% and ~1%, respectively, in premarket trading

** "We expect non-US defense demand to remain a growth vector for many years" - TD Cowen

** In a separate note, Citigroup, however, believes US aerospace industry will be insulated due to strong order books and airlines managing capacity through retirements rather than cancellations

** BA and RTX are set to report quarterly results on April 23 and April 22, respectively

** YTD, S&P 500 Aerospace & Defense .SPLRCAERO up 4%

(Reporting by Rashika Singh)

((Rashika.Singh@thomsonreuters.com;))